My Sometimes Little Sister
by Adreus
Summary: It's not like his little sister needs Ryoga's permission to date IV, really, and he's a good guy now, right, apologized and everything, it's just that... it's IV. —IV/Rio, Ryoga.


Notes: For the prompt, "IV/Rio + Shark trying really really hard to be okay with it (and kind of failing)." Fun to write, but also done before 116, so IV and Ryoga might be a little off...

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_My Sometimes Little Sister_

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So, like, here's the problem: Rio is totally allowed to date whomever she likes, because, yeah, she is indeed her own person and his being her older brother does not mean he is her keeper (he's been on the receiving end of that lecture a couple of times), and, you know, Ryoga totally trusts her judgement, he knows she won't ever even consider a relationship with someone she deems sleazy or obnoxious or bad for her, or even someone she just knows Ryoga wouldn't like, because Rio is teasing and Rio is Rio but she's still his sister, and she still cares about him. Ryoga knows this, and so he completely, doubtlessly trusts her, of course he does, it's just that, you know, sometimes—

—well, it is _slightly_ unexpected when Ryoga walks into their apartment that afternoon and finds Rio and IV with their bodies and mouths uncomfortably close.

There is, at first, a moment where the three of them are the same. Well, okay, Ryoga is standing at the door and Rio is sitting on the couch and IV is, like, halfway on top of her (and it actually looks pretty uncomfortable on both their parts), but all of their faces are the same, paled skin and wide eyes and mouths slightly open in surprise at being caught or doing the catching.

IV's the first one to move. He sort of yelps and jumps back like he's been shocked with electricity (or bit by a shark), a nice change of pace from his usual smart mouth and stupid retorts, except that the context isn't exactly the one in which Ryoga assumed he'd witness the fall of his rival. Ryoga shakes himself and IV basically flushes, and at the same time as IV and Rio both try, "Ryoga—", Ryoga narrows his eyes and says simply, "What the hell," because, really. What the hell.

The initial surprise of Ryoga's appearance chooses then to melt out of Rio, and she sighs, glances once at IV before rolling her eyes and saying, "God, will you grow a pair? If you're going to be scared of one of us, make sure it's the one you're dating."

"_Dating_?" repeats Ryoga, at the same time as IV scowls and lies, "_Hey_, I'm not scared of either of you."

"You better be," says Ryoga, glaring at him, and, fine, he doesn't actually _hate_ IV anymore, maybe even likes him a little begrudgingly (as is a little natural once someone saves your and your sister's life, right), but that doesn't mean he has to _act_ like it, because maybe IV has properly apologized and Rio has forgiven him, maybe Ryoga kinda-maybe-sorta-okay-yes enjoys bickering with him, but it was still weird seeing him in her hospital room with flowers and a card, still weird seeing him there talking to her and laughing and totally sitting in Ryoga's chair, and it's incredibly weird seeing IV in their house, a place that is barely open-doors to Yuma, never mind Kotori or Kaito or _IV_.

And, you know, it's weird seeing him trying to make out with your little sister.

(When it comes to IV she goes from _Rio_ to _my little sister (and if you touch her I will cut you up with your own cards)_ a lot — it's an instinct, really).

It's Rio's turn to glare now; she stands and crosses her arms, says, "_Ani_," to which Ryoga softens a bit but says back, "Rio," and then she sighs again and shakes her head and comes forward to greet him, "_Okaeri_," and he's startled because he was expecting something like "Get lost."

He replies with a small, surprised, "Um, _tadaima_," and she's satisfied at that, but she grabs his arm roughly anyway and pulls him to the couch before pushing him down next to IV, Ryoga protesting the entire way, and IV joining in once they're next to each other. Then she puts one hand to her hip, tells the both of them to shut it with a look, and speaks first to Ryoga.

"_Ani_," she begins, "we've talked about this."

And they have. Several times. Just that—

"We didn't talk about _him_."

"What, Ryoga," chimes IV, almost bitterly, as though he had hoped this wasn't a conversation he would actually have to be present for (or would have to happen at all), "you want to keep me all to yourself?"

Before Ryoga can get properly offended, Rio stomps on IV's foot.

(Ryoga loves his little sister).

"You're going to have to stop flirting with my brother," she says offhandedly, then returns her attention to Ryoga (who went from victoriously grinning at Rio's action to looking kind of sick at her words; IV shrugs noncommitally). "Right. As I said, we've talked about this, okay? And the two of _us_," she points at herself and then at IV, "the ones that're actually _in_ the relationship? We've talked about it. So if you're going to say I'm not _allowed_ to date him or I don't have your_permission_..."

She frowns then, and the staring contest commences, something which IV watches with interest (he's never really around them both at the same time, it's either him and Ryoga or him and Rio), but when the twins' true stamina comes to light and it starts to go on for a little too long, he gets bored, and it's when he's about to poke Ryoga so he'll give up that Ryoga slaps his hand away and grumbles, "I'm... not."

"Oh?" puts in IV, and Rio finally blinks, surprised. "Wait, really?"

Ryoga closes his eyes and wonders if this is a dream, because it'd make sense, wouldn't it, with his recent worry about Rio and his recent worry about Yuma and the recent reappearance of a particular dumbass in his life, and it's stupid enough to qualify, isn't it? But he doesn't get to close his eyes for long, because IV starts going, "Oy," and Rio gets up in his face and pulls at his cheeks and demands to know if he meant it, and he has to shove them both away and stand up before he admits, slowly, "I have no idea why you'd ever want to lock lips with this guy." He jabs his finger in IV's direction, refusing to look at him. "But... you know..."

"Know what?" asks IV, and pushes his way into Ryoga's vision. Ryoga shoves him out of it again, scowling.

"Uh, I mean, with you two..."

Ryoga shuts his eyes shut again and tries to concentrate, but Rio is grinning and it's that evil little grin that makes _my little sister_ become just _my sister_, the one that he has to peak out at and monitor and _god_—

"It's, it's up to you, I'm fi—"

"_Huuuuuh_?" bursts out IV suddenly, and now he's grinning, too, his usual mood making its triumphant return, and it's something that actually matches the look on Rio's face pretty well, now that it's in Ryoga's face and he's being forced to look at it and compare them, but at least Ryoga can punch IV and not feel guilty about it at all.

"What's this, Ryoga, are you saying you're okay with the two of us doing _this_?" IV says, and he moves back and tilts his head and raises his eyebrows at Rio, who rolls her eyes but goes to kiss him, and this time there's no flush no awkwardness just fanservice—until Rio smacks him away and shouts, "Thomas! Why're you only actually _good_ when my brother's around?!"

And there are a lot of things that Ryoga can do then, like regret his life and his decisions or simply walk away, just walk away and pretend that today didn't happen, that he doesn't know that Rio apparently has a boyfriend or that said boyfriend is Ryoga's old archrival, but instead he blinks once, blinks again, and then goes, "_Thomas_?"


End file.
